The friendly fire loss of the Russian plane is unsurprising since three of the world’s most powerful air forces – Russia, US and Israel – are frequently flying in or close to Syrian air space. In addition, there are Turkish and Syrian planes, backed up, in the case of Syria, by a ground-to-air defence system. With five air forces operating in close proximity some mishap always appeared inevitable.

Israel has expressed regret at the death of the Russian air force personnel and is concerned that the S-300s may make it more risky for its planes to continue a campaign against Iranian facilities in Syria. The missiles have the capacity to track dozens of targets at a distance of hundreds of miles. The state-owned manufacturer Almaz-Antey says they can also shoot down cruise and ballistic missiles.

Israel has long sought to prevent the delivery of the S-300s to Iran and Syria. Iran did buy the system in 2007 but it was only delivered in 2016.

“We have not changed our strategic line on Iran,” said Israeli education minister Naftali Bennett, a member of prime minister Benjamin Netanyahu’s security cabinet. “We will not allow Iran to open up a third front against us. We will take actions as required.”

Mr Putin has succeeded hitherto in maintaining good relations and a high level of cooperation with Syria, Turkey and Israel, despite their conflicting objectives in Syria.

Relations between Israel and Russia have been frayed by the 17 September shoot down when the Russians claimed that Israeli F-16s had used the reconnaissance flight of the Russian plane off Latakia to make an attack.

More is at stake than future Israeli air operations over Syria. US military power in the northern tier of the Middle East – notably in Syria and Iraq – stems primarily from the massive destructive power of its air force and its ability to use its planes and missiles at will.

This strategy worked successfully in the campaign against Isis in both countries in 2014-18 when local ground troops – the Kurds in Syria and government security forces in Iraq – defeated Isis thanks to US air support. Any radical improvement in Syrian air defences reduces US military options.

The US could not confirm yesterday that the S-300 missile batteries had been delivered. But the Russian Defence Ministry has published a video of the launcher, radar and command and control vehicle being unloaded.

Moscow will also support and upgrade Syrian electronic defences.

Syria hopes that Israel will be less free in future to carry air attacks on Syrian territory. Syria’s deputy foreign minister Faisal Mekdad said that: “Israel, which has gotten used to carrying out attacks under various pretexts, will now have to weigh and rethink before attacking again.”

The S-300 missiles will at the very least make Israel more cautious and less likely to take for granted Russian acquiescence in Israeli operations against Iran in Syria. It has also deployed the even more advanced S-400 missile batteries to its own bases in Syria.

Israel gives advanced warning to the Russians of any of its air actions in or close to Syria which has allowed some 200 attacks since the start of 2017 to be carried out in relative safety.

A Russian complaint about the shooting down of the Ilyushin reconnaissance plane is that only one minute’s warning was given. This was too short a period for them to alert the Syrians as to what was happening. An explanation for this could be that the Russians and Syrians must inevitably inform their Iranian allies about Israeli intentions leading Israel to keep the warning time as short as possible.

The shooting down of the Russian aircraft and the delivery of the S-300 is a sign that the military balance is changing to the advantage of the Syrian government.

Since the end of 2016, President Bashar al-Assad has recaptured the most important armed opposition strongholds in East Aleppo, East Ghouta and Deraa, leaving only one, the large opposition enclave in Idlib untaken. He can now focus more time to pushing back against Israeli military operations affecting Syria.

Israel and the US continue to speak of the build up of Iranian influence either directly or through local proxies in Syria, Iraq and Lebanon. But Iranian influence probably peaked in Syria and Iraq in 2015 when governments in both countries were under intense military pressure from Isis and needed all the foreign help they could get. Israeli attacks will not stop, but they will be riskier.